I like this idea. :-) The aforementioned Democracy Center is, in fact, where the aforementioned blues dance is held, and it's a nice space, though small -- it would only fit two squares, maybe three longways sets (but that might be pushing it).

One thing about difficulty level: when there's a wide mix of dancing styles, it gets harder to do advanced stuff in any one style, since even if everyone there is experienced in something, they're not going to be experienced in everything. I'd love to teach some advanced Scottish stuff to anyone who's interested (note: the RSCDS will not, in fact, kneecap you for teaching without a certificate, but it is helpful to have one, or rather the process of getting it is helpful), but that would pretty much limit the audience to people who are already experienced in Scottish (or Regency, but there aren't many of those).